72 lines
2.2 KiB
Rust
72 lines
2.2 KiB
Rust
use async_trait::async_trait;
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use crate::binary_coding::encode;
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use bincode;
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use bincode::Encode;
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use crate::cursor_capabilities::primitive::CursorCanWrite;
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use crate::cursor_capabilities::traversal::CursorCanTraverse;
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use crate::segments::entry::Entry;
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use crate::segments::store_header::StoreHeader;
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use crate::store::{FilePosition, Result};
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#[async_trait]
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pub trait CursorCanModifyEntries<T>: CursorCanTraverse<T> + CursorCanWrite<T> {
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fn header_mut(&mut self) -> &mut StoreHeader;
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fn set_eof_file_position(&mut self, new_file_position: FilePosition);
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// ===Store Header Manipulation===
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async fn increment_total_count(&mut self) -> Result<()>
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where
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T: Send,
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{
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self.seek_to_start().await?;
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self.seek_to(StoreHeader::TOTAL_COUNT_OFFSET as u64).await?;
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let new_count = self.header_mut().increment_total_count();
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self.write_bytes(&encode::<usize>(&new_count)?).await?;
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Ok(())
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}
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async fn increment_deleted_count(&mut self) -> Result<()>
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where
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T: Send,
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{
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self.seek_to_start().await?;
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self.seek_to(StoreHeader::DELETED_COUNT_OFFSET as u64)
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.await?;
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let new_count = self.header_mut().increment_deleted_count();
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self.write_bytes(&encode::<usize>(&new_count)?).await?;
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Ok(())
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}
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async fn set_header(&mut self, header: &StoreHeader) -> Result<()>
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where
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T: Send,
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{
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self.seek_to_start().await?;
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let encoded_header: Vec<u8> = header.encode()?;
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self.write_bytes(&encoded_header).await?;
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Ok(())
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}
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// ===Append Entry===
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// Moves cursor to the end.
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// Returns file position to the start of the new entry.
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async fn append_entry_no_indexing(&mut self, entry: &Entry<T>) -> Result<FilePosition>
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where
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T: Encode + Send + Sync,
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{
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self.increment_total_count().await?;
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let encoded_entry: Vec<u8> = entry.encode()?;
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let file_position = self.seek_to_end().await?;
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self.write_bytes(&encoded_entry).await?;
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let eof_file_position: FilePosition = self.current_file_position().await?;
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self.set_eof_file_position(eof_file_position);
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Ok(file_position)
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}
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}
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